That's good to know. I was thinking of adding a truss:doh:
Trussing doesnt put much more heat into the axle than weld in sleeves. I figure its cheap easy insurance against bending, and a truss only adds about 10lbs to the axle but is structurally a way better design than a sleeve. That being said make sure you have a welder who knows what they are doing before doing either and if they are trussing you have to skip around a lot and make sure you use the right rod or wire for the cast steel. Pre and post heat on the cast are important also.
Had a friend crack his axle housing about a month ago wheeling on Coyote Lake Jeep trail. He never bounced, impacted, or abused it that I saw and very rarely spun a tire and still managed to crack the passenger tube.